Jeff,
I support any and all of the suggestions that have been made, but I still doubt that your water pump is the culprit. But if you want to make absolutely sure before you try to locate another, remove the thing - a minor job after all you"ve dealt with. If the impeller blades are still, or even mostly, there and they still turn when you spin the pulley, it is doing its job. If you destroyed the gasket removing the pump, don't fret, sillicone gasket maker works fine.
Bob S.